1. Field of the Invention
The invention relates to equipment used for deicing objects or structures, and in particular to ground equipment for deicing aircraft and aircraft wings.
2. Description of the Prior Art
A deicer is a ground unit used at an airfield which is generally, but not necessarily, mobile, and which carries a tank filled with water and another filled with deicing fluid, typically a glycol. The water and the glycol are mixed on the unit at the time of delivery of the mixture. In some prior art units the constituents of the deicing fluid are premixed. In the units using non-premixed constituents in the deicing fluid, the water and possibly the glycol are heated to approximately 140 degrees F., and maintained at that temperature within the storage tank. Typically, a mobile unit includes a tank of deicing fluid of approximately 1000 to 250 gallons capacity. Given the capacity of the heating units on such mobile structures, which are typically fired or combustion units, approximately one-half hour is required to heat the 250 gallon tank to 140 degrees F. The time required to heat the fluid to the storage temperature will depend on the size of the heating unit and the amount of stored fluid.
When the deicer is to be used, it is moved to a landed aircraft whose wings are snow or ice burdened. The water and/or glycol is then heated an additional 40 degrees F., and sprayed on the airplane wing or structure. Typically, open-flame burners are used for heating the glycol water mixture to the 140 degree F. storage temperature, and then reheating the delivered glycol water mixture to the 180 degree F. delivery temperature. The size of the heating unit to first heat the fluid to the 140 degree F. storage temperature within a prescribed time, and then to heat the fluid an additional 40 degrees F to the 180 degree degree delivery temperature is a function of both the amount of fluid held in storage and the flow delivery rate. At the flow delivery rates used in the prior art, the size of the heating unit is usually determined by the flow delivery rate. Thus the heating unit is sized to provide the necessary heat input to boost the fluid to 180 degrees F. at the flow delivery rate.
Thus, prior art units typically utilize a burner, typically an open-flame burner. The presence of open-flame burners in the vicinity of aircraft is generally undesirable, and in some cases cannot be tolerated.
What is needed then, is an improved design for a deicing unit which is capable of operating without an open flame and with a smaller and more economical heating unit.